Fix mock_open() expectations for Python 3.13+

Python 3.13 introduces a behavior change in unittest.mock.mock_open(),
which now calls close() when exiting the context manager
as described in bpo-44185 [1]. This causes additional mock calls to appear,
breaking strict mock_calls assertions.

This patch fix tests and add compatibility for Python 3.13.

From mock documentation [2]:
  "bpo-44185: unittest.mock.mock_open() will call the close() method
   of the file handle mock when it is exiting from the context manager.
   Patch by Samet Yaslan."

[1] https://bugs.python.org/issue44185
[2] https://mock.readthedocs.io/en/latest/changelog.html

Change-Id: Ib8e2a8a20a828c4c69deedd307c9b726f51489f8

Author: mnasiadka

tests/test_set_config.py

@@ -48,15 +48,32 @@ def test_load_ok(self):
         with mock.patch.object(set_configs, 'open', mo):
             config = set_configs.load_config()
             set_configs.copy_config(config)
-            self.assertEqual([
-                mock.call('/var/lib/kolla/config_files/config.json'),
-                mock.call().__enter__(),
-                mock.call().read(),
-                mock.call().__exit__(None, None, None),
-                mock.call('/run_command', 'w+'),
-                mock.call().__enter__(),
-                mock.call().write('/bin/true'),
-                mock.call().__exit__(None, None, None)], mo.mock_calls)
+            if sys.version_info >= (3, 13):
+                calls = [
+                 mock.call('/var/lib/kolla/config_files/config.json'),
+                 mock.call().__enter__(),
+                 mock.call().read(),
+                 mock.call().__exit__(None, None, None),
+                 mock.call().close(),
+                 mock.call('/run_command', 'w+'),
+                 mock.call().__enter__(),
+                 mock.call().write('/bin/true'),
+                 mock.call().__exit__(None, None, None),
+                 mock.call().close()
+                ]
+            else:
+                calls = [
+                 mock.call('/var/lib/kolla/config_files/config.json'),
+                 mock.call().__enter__(),
+                 mock.call().read(),
+                 mock.call().__exit__(None, None, None),
+                 mock.call('/run_command', 'w+'),
+                 mock.call().__enter__(),
+                 mock.call().write('/bin/true'),
+                 mock.call().__exit__(None, None, None)
+                ]
+
+            self.assertEqual(calls, mo.mock_calls)
 
 
 FAKE_CONFIG_FILES = [